Integrated process for synthesizing alcohols, ethers, aldehydes, and olefins from alkanes

ABSTRACT

Alcohols, ethers, aldehydes, and olefins are manufactured from alkanes by mixing an alkane and a halogen selected from the group including chlorine, bromine, and iodine in a reactor to form alkyl halide and hydrogen halide. The alkyl halide only or the alkyl halide and the hydrogen halide are directed into contact with metal oxide to form an alcohol and/or an ether, or an olefin and metal halide. The metal halide is oxidized to form original metal oxide and halogen, both of which are recycled.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation application under 37 C.F.R. §1.63 ofapplication Ser. No. 10/208,068 filed Jul. 29, 2002 which is acontinuation-in-part application under 37 C.F.R. §1.63 of applicationSer. No. 10/054,004 filed Jan. 4, 2002, currently pending, which is acontinuation-in-part of application Ser. No. 09/951,739 filed Sep. 11,2001, currently pending, which is a continuation-in-part application ofapplication Ser. No. 09/886,078 filed Jun. 20, 2001, currently pending.

TECHNICAL FIELD

[0002] This invention relates generally to the synthesis of alcohols,ethers, aldehydes, and olefins from alkanes, and more particularly to amethod of and apparatus for manufacturing methanol and dimethyl etherfrom methane; for manufacturing ethanol, diethyl ether, ethyl acetate,and acetaldehyde from ethane; and for converting alkanes to theircorresponding olefins.

BACKGROUND OF THE INVENTION

[0003] Methane has previously been converted to methanol by thehalogenation of methane followed by hydrolysis of the methyl halide toform methanol. For example, gaseous chlorine has been used to chlorinatemethane to form chlorinated methane, principally methyl chloride,together with other chlorides, i.e., dichloromethane, trichloromethaneand carbon tetrachloride. Alternatively, methane has been subjected tooxychlorination with oxygen and hydrochloric acid to form the foregoingcompounds. The chlorinated methanes produced are hydrolyzed in the vaporphase to produce methanol, formaldehyde, formic acid and by-products,including carbon dioxide and hydrochloric acid, depending on thechlorination selectivity. Hydrochloric acid is produced or used in thehalogenation of methane by either method and must be recovered,dehydrated by azeotropic distillation and recycled. Corrosion and otherproblems involved with the handling of chlorine and hydrochloric acidare substantial.

[0004] U.S. Pat. No. 3,172,915 granted to Borkowski, et al. is directedto a process for converting methane to methanol. Borkowski discloses thechlorination of methane using ferric chloride at high temperatures toproduce chloromethanes and hydrogen chloride. The process requirestemperatures in the range of 220-800° C., more preferably 250-450° C.,and long residence times, e.g., more than one hour. Further, the processis hindered by the production of a mixture of chlorination products,e.g., chloromethane, dichloromethane, trichloromethane and carbontetrachloride, which must be separated before hydrolysis to methanol.Other disadvantages result from the energy required to dry the ferricchloride and from the corrosion and handling problems inherent withhydrochloric acid.

[0005] U.S. Pat. No. 5,243,098 granted to Miller discloses anothermethod for converting methane to methanol. In the Miller process, thereaction of methane with cupric chloride produces chloromethane andhydrochloric acid. These intermediates are then reacted with steam and acatalyst containing magnesium oxide to produce methanol and magnesiumchloride. Magnesium oxide is regenerated by treatment of the magnesiumchloride by-product with air or oxygen. Cupric chloride is regeneratedby treatment of the cuprous chloride by-product with air andhydrochloric acid. While these reactions proceed at favorable rates,attrition of the solid reactants, i.e., cupric and magnesium oxide, issignificant. Special filters and processes are required to recover andregenerate the reactants in the required particle size. Miller alsosuggests cupric bromide and magnesium zeolite as alternative reactants.Because of the attrition of the reactants, difficulties associated withthe handling of solids, and the special filters and processes requiredto regenerate the reactants, the Miller process has provedunsatisfactory. U.S. Pat. No. 5,334,777, also granted to Miller,discloses a nearly identical process for converting ethene to ethyleneglycol.

[0006] U.S. Pat. No. 5,998,679 granted to Jorge Miller, discloses aprocess for converting alkanes and alkenes to the corresponding loweralkanols and diols. In the method of the invention, a gaseous halogen(bromine) is produced by decomposing a metal halide in a liquid having amelting point below and a boiling point above the decompositiontemperature of the metal halide. The preferred liquid is molten hydratedferric chloride maintained at a temperature between about 37-280° C. Thelower alkane or alkene is halogenated in a gas phase reaction with thehalogen. The resulting alkyl halide or alkyl dihalide is contacted witha metal hydroxide, preferably an aqueous solution of ferric hydroxide,to regenerate the metal halide and produce the corresponding loweralkanol or diol. Problems with this process include low monohalogenationselectivity, and corrosiveness of the hydrated ferric halides, which maypresent a containment problem if the process is run at 280° C., wherehigh pressure steam is required to maintain ferric halide hydration.Finally, the process produces a great deal of water and HCl or HBr, allof which are difficult to separate on a large scale from the desiredproduct methanol.

[0007] Published international patent application WO 00/07718, namingGiuseppe Bellussi, Carlo Perego, and Laura Zanibelli as inventors,discloses a method for directly converting methane and oxygen tomethanol over a metal halide/metal oxide catalyst. This is not acatalyst in the true sense, however, because the reaction involvestransfer of halide from a metal halide via reaction with methane to adifferent metal oxide producing the metal halide and methanoldownstream. Eventually the halide is leached and the catalyst losesactivity.

[0008] Olah et al. (George A. Olah, et al. J. Am. Chem. Soc. 1985, 107,7097-7105) discloses a method for converting methane to methanol viamethyl halides (CH₃Br and CH₃Cl), which are then hydrolyzed to preparemethanol. In the process, CH₃Br and CH₃Cl are hydrolyzed over catalystswith excess steam generating a methanol, water, and a HCl or HBrmixture. The separation of methanol (about 2% by mole) from HCl or HBrand water on an industry scale (2000 tons per day) requires an enormousamount of energy and generates a great deal of aqueous HCl or HBr waste.Aqueous HCl and HBr are very corrosive as well.

SUMMARY OF THE INVENTION

[0009] The present invention comprises a process wherein bromine or abromine-containing compound is used as an intermediate to convertalkanes to alcohols, ethers, aldehydes, or olefins by reaction withoxygen (or air). While the process can be used to convert a variety ofalkanes, including methane, ethane, propane, butane, isobutane,pentanes, hexanes, cyclohexane etc. to their respective alcohols,ethers, aldehydes, or olefins, the conversion of methane to methanol anddimethyl ether is illustrative.

[0010] Methane reacts with a halogen selected from the group includingchlorine, bromine, and iodine to form a methyl halide and a hydrogenhalide, for example CH₃Br and HBr. The reaction may be catalytic ornon-catalytic. The methyl bromide reacts with a metal oxide to form avariable mixture of dimethyl ether (DME), water and methanol, and themetal bromide. The metal oxide and molecular bromine are regenerated byreaction of the metal bromide with air and/or oxygen. The regeneratedbromide is recycled to react with methane while the regenerated metaloxide is used to convert more methyl halide to methanol and DME,completing the reaction cycle.

[0011] The process can be easily carried out in a riser reactor.Compared to the current industrial two step process, in which methaneand steam are first converted to CO and H₂ at 800° C. followed byconversion to methanol over a Zn—Cu—Al—C catalyst at approximately70-150 atmospheres, the process of the present invention operates atroughly atmospheric pressure and relatively low temperatures, therebyproviding a safe and efficient process for methanol production.

[0012] The present invention operates with solid/gas mixtures atatmospheric pressure. In the process, the hydrogen halide is gaseous,and therefore not as corrosive as when aqueous at high temperatures. Thereaction of the halide with an alkane can reach more than 90%selectivity and high conversion to alkane-monohalide. The main sideproducts, alkane dihalides such as CH₂Br₂, can be converted back to themonohalides by reaction with an alkane. The reaction may be catalytic ornon-catalytic. Very few by-products are produced.

[0013] During operation, most of the halide atoms are trapped in thesolid state, making the system less corrosive. Another advantage is thatin the process, DME and alcohol (CH₃OH) are not produced as a mixturewith excess water. By controlling reaction conditions, almost pure DMEand/or methanol is obtained directly so that it is not necessary toseparate CH₃OH from water. Finally, in the present process, methane andoxygen do not come into direct contact, resulting in improved safety.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A more complete understanding of the present invention may be hadby reference to the following Detailed Description when taken inconnection with the accompanying Drawings, wherein:

[0015]FIG. 1 is a schematic illustration of a method of and apparatusfor synthesizing alcohols and/or ethers from alkanes comprising a firstversion of the first embodiment of the invention;

[0016]FIG. 2 is a schematic illustration of a method of and apparatusfor synthesizing alcohols and/or ethers from alkanes comprising a secondversion of the first embodiment of the invention;

[0017]FIG. 3 is a schematic illustration of a method of and apparatusfor synthesizing olefins from alkanes comprising a second embodiment ofthe invention; and

[0018]FIG. 4 is a schematic illustration of a reactor configurationuseful in manufacturing acetaldehyde from ethane.

DETAILED DESCRIPTION

[0019] Alkanes (methane, ethane, propane, butane, isobutane, pentanes,hexanes, cyclohexane etc.) react with a molecular halogen selected fromthe group including chloride, bromine, and iodine to form alkylhalides.The reaction may be catalytic or non-catalytic. Most of the by-productis CH₂Br₂ plus 2 HBr, trace amounts of CHBr₃ and CBr₄, which can becatalytically reconverted to CH₃Br by reacting CH₂Br₂, CHBr₃, and CBr₄with CH₄.

[0020] Referring to the Drawings, and particularly to FIG. 1, a methodand apparatus 10 for synthesizing alcohols and ethers from alkanes usinga halogen selected from the group including chloride, bromine and iodinecomprising a first version of the first embodiment of the invention isschematically illustrated. In the operation of the method and apparatus10, a halide, for example, bromine is received from a suitable sourcethrough a line 12 and is directed to a bromine storage container 14. Asis well known, bromine is easily manufactured from bromide, which isreadily available from sea water.

[0021] As is also well known, bromine is a liquid at room temperature.Liquid bromine from the storage container 14 is directed through a line16 to a bromine vaporizer 18 wherein the bromine is converted from theliquid phase to the gas phase. From the vaporizer 18 the gaseous bromineis directed through a line 20 to a reactor 22.

[0022] Methane from a suitable source is directed to the reactor 22through a line 24. Within the reactor 22 the methane and the gaseousbromine are mixed together over an appropriate solid catalyst, and thetemperature of the mixture is raised to between about 20° C. and about600° C., thereby converting the methane and the bromine to methylbromide (CH₃Br) and hydrogen bromide (HBr).

[0023] From the reactor 22, the CH₃Br, the HBr, any unreacted methaneand by-products CH₂Br₂, CHBr₃, and CBr₄ are directed to a condenser 34through a line 30. The by products CH₂Br₂, CHBr₃, and CBr₄ are in theliquid state and are sent through a line 32 to a converter 28 to reactwith methane. In the converter 28 methane reacts with the by productsCH₂Br₂, CHBr₃, and CBr₄ to form CH₃Br. The newly formed CH₃Br andunreacted CH₂Br₂, CHBr₃, CBr₄ and methane are sent to the condenser 34through a line 26 and the line 30.

[0024] From the condenser 34 gas phase methane, HBr, and CH₃Br are sentto a converter 52 through a line 36. In the converter 52 HBr and CH₃Brreact with metal oxide to form CH₃OCH₃, CH₃OH, and H₂O, which are sentto a separator 44 along with unreacted methane and CH₃Br through a line46.

[0025] In the separator 44 dimethyl ether and methanol/water areseparated as products and recovered at outlets 40 and 48, respectively.The methanol is subsequently removed from the water by distillation.CH₃Br is sent back to the converter 52 through the line 38 and the line36. Methane from the separator 44 is sent back to the brominationreactor 22 through the line 42 and the line 24.

[0026] In the converter 52, the original metal oxide is converted tometal bromide and must be regenerated. The metal bromide from theconverter 52 is sent to a converter 58 through a line 54 to react withoxygen received from a source 74 through a line 72 to regenerate bromineand metal oxide. The regenerated metal oxide is sent back to theconverter 52 through a line 56, while the bromine and unreacted oxygenare sent to a condenser 62 through a line 60, after which they areseparated in a separator 68. The liquid bromine is sent to the storagecontainer 14, while the oxygen is sent to the converter 58 through ablower 66 and a line 70.

[0027] Referring to FIG. 2, there is shown a method of and apparatus 100for synthesizing alcohols and ethers from alkanes comprising a secondversion of the first embodiment of the invention. The method andapparatus 100 can be used with alkanes such as methane, ethane, propane,butane, isobutene, pentanes, hexanes, cyclohexane, etc. The method andapparatus 100 also employs a halide selected from the group includingchlorine, bromine, and iodine.

[0028] For example, methane and bromine are directed to a heat zone andvaporizer 102 where the bromine is converted from a liquid to a gas andmixed with methane at a temperature above the atmospheric boiling pointof bromine. The gas mixture is passed into a bromination reactor 104containing an appropriate solid catalyst. After the reaction, themixture is directed to condenser a 106. The liquid phase contains byproducts CH₂Br, CHBr₃, and CBr₄, while the gas phase containsbromomethane, HBr, and unreacted methane.

[0029] The by products CH₂Br₂, CHBr₃, and CBr₄ are sent to a converter108 where they react, either catalytically or non-catalytically, withmethane to form bromomethane. After the reaction the mixture is sent tothe condenser 106.

[0030] The conversion of the by products CH₂Br₂, CHBr₃, and CBr₄ tobromomethane in the converter 108 can be facilitated by the use of anelectrophilic catalyst such as AlBr₃, SbF₅, etc. which provides a lowbarrier pathway allowing direct four centered exchange of H and Br. Thereaction may be represented as follows:

ΔCH₄+CBr₄+AlBr₃(cat)−→CH₃Br+CHBr₃+AlBr₃

[0031] The overall reaction is isothermic and therefore may be driven byfractional recovery of higher bromides and removal of bromomethane fromthe reaction mixture, all in the presence of excess methane.

[0032] The gas phase mixture from the condenser 106 is passed through aconverter 110, where HBr reacts with the metal oxide to form metalbromide and water. The metal bromide is sent to a regenerator 120 toregenerate metal oxide. From the converter 110, the water, bromomethane,and methane are separated in a separator 112. Methane is recycled to theconverter 108 and the vaporizer 102. Bromomethane is sent to the reactor114. Water is sent to the reactor 118.

[0033] In the reactor 114 bromomethane reacts with metal oxide togenerate dimethyl ether (DME) and metal bromide. Metal bromide is sentto the regenerator 120. The mixture of bromomethane and DME from thereactor 114 is sent to a separator 116. Bromomethane is recycled to thereactor 114, while DME is obtained as a product or directed to reactor118. In the reactor 118 DME reacts with water (from the separator 112)to form methanol. The reaction may be catalytic or non-catalytic.

[0034] In the regenerator 120 metal bromide from the converter 110 andthe reactor 114 reacts with air or oxygen to regenerate metal oxide andbromine. After regeneration the metal oxide is sent to the converter 110and the reactor 114, while bromine is sent to the vaporizer 102. If airis used to provide the oxygen for metal oxide regeneration nitrogen maybe purged from the system through the separator 122.

[0035] Referring to FIG. 3, there is shown a method and apparatus 200for synthesizing olefins from alkanes, comprising a second embodiment ofthe invention. The alkane and a halide selected from the group includingchlorine, bromine, and iodine are directed to a heat zone and, whenbromine is used, a vaporizer 202, operating at a temperature above theatmospheric boiling point of bromine, where the now gaseous bromine andmethane are allowed to mix. The gas mixture is passed into a brominationreactor 204. After the reaction, which may be catalytic ornon-catalytic, the mixture is directed to a condenser 206. The heavieralkane multibromides (below 1%) are separated for other uses, such assolvent or intermediates for other organic synthesis at an outlet 208,while the alkane monobromide, HBr, and unreacted alkane are sent to areactor 210.

[0036] In the reactor 210 HBr reacts with metal oxide to form metalbromide and water. The metal bromide is sent to a regenerator 220 to beregenerated back to metal oxide. From the converter 210 the water,alkane monobromide, and alkane are separated in a separator 212.Unreacted alkane is recycled to the vaporizer 202, while the alkanemonobromide is sent to a reactor 214. Water is easily separated from thealkane monobromide in the separator 212 as a by product.

[0037] In the reactor 214 alkane monobromide reacts with metal oxide togenerate olefin and metal bromide. Metal bromide is sent to theregenerator 220 for regeneration back to metal oxide. The mixture ofolefin and unreacted alkane monobromide from the reactor 214 is sent toa separator 216 where they are easily separated due to their widelydifferent boiling points. Unreacted alkane monobromide, if any, isrecycled to the reactor 214, while olefin is obtained as a product.

[0038] In the regenerator 220 metal bromide from the converter 210 andthe reactor 214 reacts with air or oxygen to regenerate metal oxide andbromine. After regeneration metal oxide is sent to the reactor 210 andthe reactor 214, while bromine is sent to the vaporizer 202. If air isused as the source of oxygen for regeneration of the metal oxidenitrogen may be purged from the system by a separator 222.

EXAMPLES

[0039] Reaction 1:

[0040] Catalyst Preparation

[0041] Nb₂O₅ (0.8000 g) was mixed with 0.500 ml 96(w)% H₂SO₄, then themixture was heated at 110° C. for 4 hours. The temperature increased to500° C. within 6 hours, and kept at 500° C. for 4 hours. Catalyst C1 wasobtained.

[0042] ZrO₂ (2.0000 g) was mixed with H₂SO₄ (3.000 ml, 96(w)%), then themixture was heated at 110° C. for 4 hours. The temperature increased to500° C. within 6 hours, and kept at 500° C. for 4 hours. Catalyst C2 wasobtained.

[0043] Testing

[0044] Reaction Conditions:

[0045] The catalyst was tested at a methane flow of 1.5 ml/minute andBr₂ flow of 0.07 ml/hour. The reaction temperature was 400° C. Thereaction was carried out in a micro reactor system. After 6 hours online reaction, the reaction effluent was analyzed by a GC/MS, and showeda 23% methane conversion with 55% selectivity to CH₃Br.

[0046] Summarizing the overall process in Reaction 1:

CH₄+Br₂>HBr+CH₃Br+CH₂Br₂+CHBr₃ +CBr₄ cat   (1)

Example 1

[0047] Reaction 2:

[0048] Reaction on M1

[0049] For all of the examples provided above the second stage of theprocess occurs as follows. After separation of the CH₂Br₂, CHBr₃ andCBr₄ products from the gas stream, the CH₃Br, together with the HBr arepassed into the next reactor, which contains M1 (50% CuO on ZrO₂) and ismaintained at 225° C. Flowing the reactant gases at 10 h⁻¹ gives a 96%conversion of CH₃Br+HBr to CH₃OCH₃ and H₂O, or to CH₃OH, or a mixture ofCH₃OH, CH₃OCH₃, and H₂O, with 94% selectivity, the remaining productbeing CuBr₂/ZrO₂ and 6% CO₂. Dimethyl ether and water are converted intomethanol if desired in a third reactor containing catalysts.

Example 2

[0050] Zr Solution Preparation

[0051] Zr(OCH₂CH₂CH₃)₄ (70(w)% in isopropanol, 112.6 ml) was dissolvedinto acetic acid (275 ml) under stirring. After stirring for 10 minutes,the solution was diluted by water to make a total volume of 500 ml. Asolution with a Zr concentration of 0.5M was obtained.

[0052] Preparation of M2

[0053] Cu(NO₃)₂ (0.5M, 7.200 ml) solution was added into BaBr₂ (0.5M,0.800 ml). A clear solution was obtained. To this solution, Zr solution(0.5M) as prepared above was added under stirring. After stirring a fewseconds, a gel was obtained. The gel was dried at 110° C. for 4 hours,then heated to 500° C. within 6 hours, and kept at 500° C. for 4 hours.M2 was obtained.

[0054] The metal oxide mixture was tested at a CH₃Br flow rate of 1.0ml/minute at 230° C. In the first half hour, the average CH₃Brconversion was 65%, and the average dimethyl ether selectivity was90.5%.

[0055] Preparation of M3

[0056] Cu(NO₃)₂ (0.5M, 40.000 ml) solution was added into Zr solution(0.5M, 30.000 ml as prepared above). After stirring a few seconds, a gelwas obtained. The gel was dried at 110° C. for 4 hours, then heated to500° C. within 6 hours, and calcined at 500° C. for 4 hours. M3 wasobtained.

[0057] Testing

[0058] The catalyst C2 (2.0000 g) was loaded in the first reactor (R1).A trap was loaded with 2.000 g of M3. A second reactor (R2) was loadedwith M3 (0.8500 g).

[0059] Reactants methane and bromine were fed into the first reactor(methane flow of 1.5 ml/minute, Br₂ flow of 0.07 ml/hour). The reactiontemperature was 390° C. After reaction in R1 (stabilized by onlinereaction for more than 8 hours) the resulting mixture was passed throughthe trap and a mixture of methane and CH₃Br (in a 85:15 molar ratio) wasobtained. This gas mixture was fed directly into reactor R2 at 220° C.In the first hour an average CH₃Br conversion of 91% with an averagedimethyl ether selectivity of 75% was obtained. Summarizing the overallprocess in Reaction 2:

CH₃Br+HBr+CuO>CH₃OH+CuBr₂   (2)

[0060] Possible variations of Reaction 2:

2 HBr+CuO>H₂O+CuBr₂   (2a)

2 CH₃Br+CuO>CH₃OCH₃+CuBr₂   (2b)

[0061] Reaction 3:

[0062] The solid CuBr₂/ZrO₂ was transferred from Reactor 2 to Reactor 3and treated with O₂ at 300° C. to yield Br₂ and CuO/ZrO₂ at 100% yieldand conversion. This reaction may be run at 1000 h⁻¹.

[0063] Summarizing the overall process in Reaction 3:

CuBr₂/ZrO₂+½O₂>Br₂+CuO/ZrO₂   (3)

[0064] Overall:

CH₄+½O₂>CH₃OH   (A)

[0065] Possible variation:

CH₄+½O₂>½CH₃OCH₃+½H₂O   (B)

[0066] A third embodiment of the invention comprises a process forconverting ethane to diethyl ether, ethanol, and ethyl acetate which maybe carried out as illustrated in FIGS. 1, 2, and 3. In the process,ethane reacts with a halogen selected from the group including chlorine,bromine, and iodine. For example, ethane is reacted with bromine to formbromomethane and HBr. The bromoethane then reacts with metal oxide toform diethyl ether, ethanol, ethyl acetate, and metal bromide. The metalbromide reacts with oxygen or air to regenerate the original metaloxide. In the process, bromine and metal oxide are recycled.

[0067] In the ethane/bromine reaction the ethane to bromine ratio ispreferably between about 10:1 and about 1:10, and more preferably about4:1. The temperature range for the ethane/bromine reaction is preferablybetween about 100° C. and about 500° C. and more preferably betweenabout 300° C. and about 400° C. The ethane/bromine reaction can beeither catalytic or non-catalytic, it being understood that if asuitable catalyst is used the selectivity to ethane monobromide ordibromides can be high. The reaction is slightly exothermal and is veryeasy to control.

[0068] The second reaction is preferably carried out a temperature rangeof between about 150° C. to about 350° C., and more preferably within atemperature range of about 200° C. to about 250° C. Bromoethane isconverted to diethyl ether with 60 to 80% conversion with about 4%selectivity to ethanol and about 3% selectivity to ethyl acetate. Hence,high diethyl ether yield with useful ethanol and ethyl acetate byproducts is obtained in a single pass. In the process, there is nodirect contact between oxygen and ethane thereby providing a high levelof safety. If desired, the diethyl ether can be easily hydrolyzed toethanol with water over a suitable catalyst.

EXAMPLE

[0069] Part A. Ethane Bromination Reaction

[0070] A mixture of ethane (6.0 ml/minute) and bromine (Br₂ 0.30ml/hour) was passed into a reactor (glass tube, ID 0.38″, heating zonelength 4″), and was heated to 330° C. The effluent was analyzed byGC/MS. 100% bromine conversion with 80% bromoethane selectivity wasobtained. The by product with 20% selectivity was 1,1-dibromoethane. The1,1-dibromoethane can be converted to bromoethane by reaction withethane over a catalyst, such as a metal compound or a mixture of metalcompounds.

[0071] The ethane bromination reaction can also be a catalysis reaction.The catalysts are compounds of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re,Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl,Si, Ge, Sn, Pb, P, Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li,K, O, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb, Lu, and Cs or mixturesthereof. The reaction is preferably carried out at a temperature rangeof between about 50° C. to about 600° C. The reaction pressure ispreferably from about 1 to about 200 atm. The reaction mixture can havea ratio of ethane to bromine from 0.1 to 100.

[0072] Part B. The Reaction of Bromoethane with Metal Oxides.

[0073] Zr Solution Metal Oxide Preparation

[0074] Zr(OCH₂CH₂CH₃)₄ (70(w)% in isopropanol, 112.6 ml) was dissolvedinto acetic acid (275 ml) under stirring. After stirring for 10 minutes,the solution was diluted with water to make a total volume of 500 ml. Asolution with a Zr concentration of 0.5M was obtained.

[0075] Preparation of M4

[0076] A Cu(NO₃)₂ (0.5M, 64.0 ml) solution was added into a Zr solution(0.5M, 64.0 ml) (as prepared above). After stirring for a few seconds, agel was obtained. The gel was dried at 110° C. for 4 hours, then heatedto 500° C. within 6 hours, and calcined at 500° C. for 4 hours. CuO/ZrO₂metal oxide (M4) was obtained.

[0077] Testing

[0078] Bromoethane (0.20 ml/hour) and helium (4.0 ml/minute) were passedthrough a reactor that was packed with 3.0000 grams M4, which was heatedto 200° C. Within the first hour, an average bromoethane conversion of70% was observed and diethyl ether in 50 to 60% selectivity wasobtained. The ethanol selectivity was about 4% and ethyl acetateselectivity was about 3%.

[0079] In the above reaction, the metal oxides can be oxides of thefollowing metals: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co,Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, Si, Ge, Sn,Pb, P, Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li, K, La, Ce,Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb, Lu, and Cs or mixtures thereof.

[0080] The reaction can be carried out at a temperature range from about50° C. to about 600° C. The reaction pressure is preferably from about 1to about 200 atm. The reaction can be carried out with or withouthelium. The metal bromide is converted to metal oxide M4 in oxygen or inair to obtain metal oxide and bromine at a temperature range of about 50to about 700° C. and pressure range from about 1 to about 300 atm.

[0081] A fourth embodiment of the invention comprises a process forconverting ethane to acetaldehyde, which may be carried out asillustrated in FIGS. 1, 2, and 3. In the process, ethane is reacted witha halogen selected from the group including chlorine, bromine, andiodine. For example, ethane can be reacted with bromine to formbromoethane and HBr. In the bromination reaction the ethane to bromineratio is preferably between about 10:1 and about 1:10, and morepreferably about 4:1. The temperature range for the bromination reactionis preferably between about 100° C. and about 500° C., and morepreferably between about 300° C. and about 400° C.

[0082] The bromoethane then reacts with metal oxide to form acetaldehydeand metal bromide. The second reaction is preferably carried out at atemperature range of between about 150° C. and about 350° C., and morepreferably at a temperature range of between about 200° C. and about250° C. The metal bromide is reacted with oxygen or air to regeneratethe original metal oxide. In the process, bromine and metal oxide arerecycled.

EXAMPLE

[0083] Ethane and bromine were thermally reacted at 350° C in a firstreactor comprising an empty glass tube (ID 0.38″, heating zone length4″) by feeding ethane and bromine at a 3.6:1 mol ratio, respectively(ethane=4 ml/min and Br₂=0.14 ml/h). The reaction products comprisingthe outlet gas were analyzed by gas chromatography (GC) and a flameionization detector (FID) during the reaction using nitrogen gas as aninternal standard. The GC/FID results showed that the reaction achieved23% ethane conversion. The reaction products comprising the outlet gaswere also collected into a CDCl₃ solution cooled in a dry-ice acetonebath for nuclear magnetic resonance (NMR) analysis. The NMR resultsdemonstrated a product distribution in mol percents of 76.8%monobromoethane, 19.3% 1,1 dibromoethane, and 3.8% 1,2 dibromoethane.

[0084] A second reaction was initiated by directing the reactionproducts from the first reaction to a second reactor comprising a glasstube (ID 0.38″, heating zone length 4″) containing 5g of a metaloxidecomprising CaO/CuO/TiO₂. The second reaction took place at 250° C. andproduced acetaldehyde. After a 1 h reaction the NMR spectrum of productscollected in a CDCl₃ solution cooled in a dry-ice acetone bathdemonstrated that the reaction achieved 100% bromoethane anddibromoethane conversion. The relative distribution of liquid productsisolated (in C₂ equivalents) was 59.13% acetaldehyde, 8.53%ethylacetate, 5.36% diethylether, 16.47% ethanol and 10.52%vinylbromide. GC analysis of the gas escaping the CDCl₃ trap revealedthe formation of CO₂ (15% of brominated ethanes entering the secondreactor) and ethylene (15%) as well.

[0085] Preparation of the Ti Solution: Ti[OCH(CH₃)₂]4 (97%, 76.7 ml) wasdissolved in an oxalic acid solution(56.5 g oxalic acid dissolved in 200ml distilled water) by heating and stirring for two hours. After twohours, the solution was diluted by water to the total volume of 500 ml.0.5M Ti Solution was obtained.

[0086] Preparation of the Metaloxide: Aqueous solutions comprising 20 mlof 0.5M Cu(NO₃)₂ and 20 ml of 0.5M CaBr₂ were mixed in 40 ml of 0.5M TiSolution (prepared as described above). After stirring the mixture 10minutes it was dried at 120° C. for 4 hours, then heated to 500° C.within 6 hours, and calcined at 500° C. for 4 hours. CaO/CuO/TiO₂ wasobtained containing 25% each Ca and Cu and 50% Ti in mol percentages.

[0087] The Reactor System: Referring to FIG. 4, ethane bromination andthe second reaction were performed in a three-zone reactor. Ethane andbromine were fed into the bottom of reactor zone 1 which was otherwiseempty to produce bromoethane. The reactor zones contained the solidmetaloxide CaOCuOTiO₂ for the oxidation reaction of bromoethane. Thereactor zone 2 comprised a glass balloon trap between the two reactors,at room temperature, to reflux and collect any dibromoethane produced inthe reactor zone 1. The reactor zone 2 is charged through another inletfor the addition of water to the 2^(nd) reactor system as required.

EXAMPLE

[0088] The reaction of ethyl bromide at 250C. over 3 g of several timesused and regenerated CuO/ZrO2 with ethane as a carrier gas producedacetaldehyde at 21% selectivity (estimated) during the 2^(nd) hour ofthe reaction period. The distribution of other products was 15% ethanol,5% diethyl ether, 20% ethyl acetate and 3% butadiene.

[0089] Preparation of the Zr Solution: 112 ml of Zr(OCH₂CH₂CH₃)₄ (70% wtin 1-propanol) solution was dissolved into an oxalic acid solution(56.5g oxalic acid dissolved in 200 ml distilled water) under stirring. Afterstirring for 2 hours, the solution was diluted by water to make a totalvolume of 500 ml. A solution comprising a Zr concentration of 0.5M wasobtained.

[0090] Preparation of CuO/ZrO₂: Aqueous solutions of 50 ml of 0.5MCu(NO₃)₂ solution and 50 ml of 0.5M Zr solution (prepared as describedabove) were mixed. After stirring a few seconds, a gel was obtained. Thegel was dried at 120° C. for 4 hours, then heated to 500° C. within 6hours, and calcined at 500° C. for 4 hours. CuO/ZrO₂ was obtainedcomprising 50% mol Cu and 50% mol Zr A fifth embodiment of the inventioncomprises a process for converting saturated hydrocarbons (alkanes) totheir corresponding olefins. For instance, ethane to ethylene, propaneto propylene, butane to butene or butadiene, isobutane to isobutene,etc. The process of the fifth embodiment may be carried out asillustrated in FIGS. 3.

[0091] In the process, alkane reacts a halogen selected from the groupincluding chlorine, bromine and iodine to form halogenated alkane andhydrogen halide. The halogenated alkane then reacts with metal oxide toform olefin and metal halide. The metal halide reacts with oxygen or airto regenerate the metal oxide. In the process, halogen and metal oxideare recycled.

[0092] In the prior art, olefins are made by hydrocarbon thermalcracking. The thermal cracking process also produces saturatedhydrocarbons, such as propane, butane, isobutane, pentanes, and hexanes,which are usually difficult to convert to useful materials. For example,ethane can be converted to ethylene by thermal cracking at temperaturesover 800° C. in an endothermic reaction, which consumes large amounts ofenergy, and also generates about 30% by product acetylene (C₂H₂). Theacetylene must be hydrogenated back to ethylene which usually leads toover hydrogenation to ethane.

[0093] Propane is currently used as fuel, since there presently existsno efficient process that can convert propane to propylene.

[0094] There has been research directed at oxidizing alkanes to theircorresponding olefins by reacting the alkane with oxygen over catalysts.However, low selectivity and low conversion rates were obtained. Thereaction generates large amounts of heat, which can melt the catalyst aswell as the reactor. Further, most of these processes involve the directcontact of the alkane with oxygen at high temperature and pressure,which is potentially dangerous.

[0095] It is well known that alkanes can easily react with CBr₄ , CHBr₃,or CH₂Br₂, or react with bromine at low temperatures (below 400° C.) toform alkane monobromides or alkane dibromides. The reaction can becatalytic or non-catalytic. If a suitable catalyst is used, theselectivity to alkane monobromide or dibromide can be very high (morethan 95% CH₃CH₂BrCH₃ selectivity can be reached). The reaction isslightly exothermal and is very easy to control. In the next reaction,alkane bromide is converted to olefin with 100% conversion (one pass)and selectivity over 95%. Hence, high olefin yield can be obtained in asingle pass. In the process, the direct contact of oxygen with alkane isavoided, making the operation safe. A further advantage of the presentinvention is the virtual elimination of byproducts, rendering recoveryof the desired olefin substantially easier then the conventionalprocess. An even further advantage of the present invention is theproduction of the olefin without the production of the correspondingalkyne, thus eliminating the need for partial hydrogenation.

[0096] The alkane/bromine reaction is preferably carried out at analkane to bromine ratio of between about 10:1 and about 1:10, and morepreferably at an alkane to bromine ratio of about 4:1. The temperaturerange of the first reaction is preferably between about 100° C. andabout 500° C., and more preferably between about 300° C. and about 400°C. The second reaction is preferably carried out at a temperature ofbetween about 150° C. and about 350° C., and more preferably at atemperature between about 200° C. and about 250° C.

EXAMPLE

[0097] Part A. Alkane Bromination Reaction

[0098] Propane Bromination Reaction

[0099] A mixture of propane (6.0 ml/minute) and bromine (Br₂ 0.30ml/hour) was passed into a reactor (glass tube ID 0.38″, heating zonelength 4″), which was heated to 270° C. The effluent was analyzed byGC/MS. 100% bromine conversion with 88.9% 2-bromopropane selectivity and11.1% 1-bromopropane selectivity were obtained.

[0100] This reaction can also be a catalysis reaction. The catalysts arecompounds of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh,Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb,P, Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li, K, O, La, Ce,Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb, Lu, and Cs or mixtures of suchcompounds. The reaction can be carried out at a temperature range fromabout −10° C. to about 600° C. The reaction pressure can be from about 1to about 200 atm. The reaction mixture can have a ratio of propane tobromine from 0.1 to 100.

[0101] Bromination of Isobutane

[0102] A mixture of isobutane (6.0 ml/minute) and bromine (Br₂ 0.30ml/hour) was passed into a reactor (glass tube ID 0.38″, heating zonelength 4″), which was heated to 220° C. The effluent was analyzed byGC/MS. 100% bromine conversion with 97% 2-bromo-2-methyl-propaneselectivity was obtained.

[0103] This reaction can also be a catalysis reaction. The catalysts arecompounds of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh,Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, Si,. Ge, Sn, Pb,P, Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li, K, O, La, Ce,Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb, Lu, and Cs or mixtures of suchcompounds. The reaction can be carried out at a temperature range fromabout −10° C. to about 600° C. The reaction pressure can be from about 1to about 200 atm. The reaction mixture can have a ratio of isobutane tobromine from 0.1 to 100.

[0104] Part B. The Reaction of Alkane Bromides with Metal Oxides

[0105] Preparation of Zr Solution Metal Oxide

[0106] Zr(OCH₂CH₂CH₃)₄ (70(w)% in isopropanol, 112.6 ml) was dissolvedinto acetic acid (275 ml) under stirring. After stirring for 10 minutes,the solution was diluted with water to make a total volume of 500 ml. Asolution with a Zr a concentration of 0.5M was obtained.

[0107] Preparation of M5

[0108] Cu(NO₃)₂ (0.5M, 4.00 ml) solution was added into CaBr₂ (0.5M,4.00 ml). A clear solution was obtained. To this solution, Zr solution(0.5M, 8.0 ml) as prepared above was added under stirring. Afterstirring for a few seconds, a gel was obtained. The gel was dried at110° C. for 4 hours, then heated to 500° C. within 6 hours, and calcinedat 500° C. for 4 hours. M5 was obtained.

[0109] Preparation of M6

[0110] Cu(NO₃)₂ (0.5M, 7.20 ml) solution was added into BaBr₂ (0.5M,0.80 ml). A clear solution was obtained. To this solution, Zr solution(0.5M, 8.0 ml) as prepared above was added under stirring. Afterstirring for a few seconds, a gel was obtained. The gel was dried at110° C. for 4 hours, then heated to 500° C. within 6 hours, and calcinedat 500° C. for 4 hours. M6 was obtained.

[0111] Preparation of M7

[0112] A Cu(NO₃)₂ (0.5M, 8.00 ml) solution was added into Zr solution(0.5M, 8.0 ml) as prepared above was added under stirring. Afterstirring for a few seconds, a gel was obtained. The gel was dried at110° C. for 4 hours, then heated to 500° C. within 6 hours, and calcinedat 500° C. for 4 hours. M7 was obtained.

[0113] Testing on M5

[0114] 2-bromopropane (0.25 ml/hour) and nitrogen (5.0 ml/minute) werepassed through a reactor (glass tube ID 0.38″, heating zone length 4″)that was packed with 0.8701 gram M5 and heated to 200° C. 100%2-bromopropane conversion with more than 95% propylene selectivity wasobtained within the first 40 minutes. As the reaction proceeds, the CuOis converted to CuBr₂, and the 2-bromopropane conversion rate decreases.When the reaction was carried out at 180° C., within the beginning 10minutes, 99% propylene selectivity was reached with 2-bromopropaneconversion more the 60%.

[0115] 1-bromo-2-methyl-propane (0.29 ml/hour) and nitrogen (5.0ml/minute) were passed through a reactor (glass tube ID 0.38″, heatingzone length 4″) that was packed with 0.8701 gram M5 and heated to 220°C. 100% 1-bromo-2-methyl-propane conversion with more than 96%2-methyl-propylene selectivity was obtained within the first hour. Asthe reaction progresses and the CuO is converted to CuBr₂, the2-bromopropane conversion decreases.

[0116] 1-bromo-propane (0.24 ml/hour) and nitrogen (5.0 ml/minute) werepassed through a reactor (glass tube ID 0.38″, heating zone length 4″)that was packed with 0.8701 gram M5 and heated to 220° C. 100%1-bromo-propane conversion with more than 90% propylene selectivity wasobtained within the first 20 minutes.

[0117] 2-bromo-2-methyl-propane (0.31 ml/hour) and nitrogen (5.0ml/minute) were passed through a reactor (glass tube ID 0.38″, heatingzone length 4″) that was packed with 0.8701 gram M5 and heated to 180°C. 100% 2-bromo-2-methyl-propane conversion with more than 96%2-methyl-propylene selectivity was obtained within the first hour.

[0118] Testing on M6

[0119] A mixture of 1-bromopropane and 2-bromopropane (volume 1:1) (0.25ml/hour) and nitrogen (5.0 ml/minute) was passed through a reactor(glass tube ID 0.3811, heating zone length 4″) that was packed with0.8980 gram M6 and heated to 200° C. 100% reactant conversion with morethan 90% propylene selectivity was obtained within the first 10 minutes.

[0120] Testing on M7

[0121] A mixture of 1-bromo-2-methyl-propane and2-bromo-2-methyl-propane (volume 1:1) (0.30 ml/hour) and nitrogen (5.0ml/minute) were passed through a reactor (glass tube ID 0.38″, heatingzone length 4″) that was packed with 0.8500 gram M7 and heated to 220°C. 100% reactant conversion with more than 95% propylene selectivity wasobtained within the first 40 minutes.

[0122] The metal oxides used above can be oxides of the followingmetals: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir,Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P,Sb, Bi, S, Cl, Br, F, Sc, Y, Mg, Ca, Sr, Ba, Na, Li, K, La, Ce, Pr, Nd,Sm, Eu, Gd, Tb, Er, Yb, Lu, and Cs and mixtures thereof. The reactioncan be carried out at a temperature range from about 50° C. to about600° C. The reaction pressure can be from about 1 to about 200 atm. Thereaction can be carried out with or without nitrogen. The metal bromidewas converted to metal oxide (M5, M6, and M7) in oxygen or in air toobtain metal oxide and bromine at a temperature range of about 50 toabout 700° C. under pressure range from about 1 to about 300 atm.

[0123] It will therefore be understood that the method and apparatus ofthe present invention operates on a continuous or batch basis to convertalkanes to alcohols, ethers, and olefins. The method and apparatus ofthe present invention operates at relatively low temperatures and at lowpressures and is therefore economical to manufacture and use. Thebromine, which is utilized in the method and apparatus of the presentinvention, is continuously recycled. The metal oxide, which is utilizedin the process is continuously refreshed.

[0124] Although preferred embodiments of the invention have beenillustrated in the accompanying Drawings and described in the foregoingDetailed Description, it will be understood that the invention is notlimited to the embodiments disclosed but is capable of numerousrearrangements, modifications, and substitutions of parts and elementswithout departing from the spirit of the invention.

1. A method for converting ethane to acetaldehyde comprising: providinga quantity of ethane; providing a quantity of at least one halogenselected from the group including chlorine, bromine, and iodine;reacting the ethane with the halogen and thereby forming haloethane andhydrogen halide; directing at least the haloethane into engagement witha metal oxide and thereby forming acetaldehyde and a metal halide. 2.The method according to claim 1 including additional steps of: oxidizingthe metal halide to form the original metaloxide and halogen; recyclingthe metaloxide; and recycling the halogen.
 3. The method according toclaim 1 wherein the step of reacting the ethane with the halogen iscarried out in the presence of excess ethane.
 4. The method according toclaim 1 wherein the step of reacting ethane with halogen is carried outat a mole ratio of about 4:1 ethane to halogen.
 5. The method accordingto claim 1 wherein the step of directing the haloethane into engagementwith a metaloxide is carried out by directing the haloethane intoengagement with a metaloxide selected from the group includingCaO/CuO/TiO₂ and CUO/ZrO₂.
 6. The method according to claim 1 whereinthe step of directing the haloethane into engagement with a metaloxideis carried out by directing the bromoethane into engagement with ametaloxide comprising CaO/CuO/TiO₂.
 7. The method according to claim 6wherein the mol ratios of the components of the metaloxide are 25% CaO,25% CuO, and 50% TiO₂.
 8. The method according to claim 1 wherein thestep of directing the haloethane into engagement with a metaloxide iscarried out by directing the haloethane into a metaloxide comprisingCuO/ZrO₂, and wherein the metaloxide comprises a mol ratio of 50% CuO₂and 50% Zr O₂.
 9. A method of converting ethane to acetaldehydecomprising: providing a first reactor zone; providing a quantity ofethane; providing a quantity of a halogen selected from the groupincluding chlorine, bromine, and iodine; reacting the ethane with thehalogen in the first reactor zone and thereby forming haloethane;providing a second reactor zone; providing a third reactor zone;providing a quantity of a metaloxide within the third reactor zone;directing the haloethane from the first reactor zone through the secondreactor zone to the third reactor zone for reaction with the metaloxidetherein to form acetaldehyde and metal halide.
 10. The method accordingto claim 9 wherein the reaction of ethane and halogen in the firstreactor zone is carried out at about 350° C.
 11. The method according toclaim 9 wherein the second reactor zone is maintained at roomtemperature, and wherein any dihaloethane produced during theethane/halogen reaction in the first reactor zone is refluxed andcollected in the second reactor zone.
 12. The method according to claim9 wherein the reaction of the haloethane with the metaloxide in thethird reactor zone is carried out at a temperature of between about 250°C. and about 300° C.
 13. The method according to claim 9 includingadditional steps of: oxidizing the metal halide from the third reactorzone to form the original metaloxide and halogen; recycling themetaloxide; and recycling the halogen.
 14. The method according to claim9 wherein the step of reacting the ethane with the halogen is carriedout in the presence of excess ethane.
 15. The method according to claim9 wherein the step of reacting ethane with the bromine is carried out ata mole ratio of about 4:1 ethane to halogen.
 16. The method according toclaim 9 wherein the step of directing the haloethane into engagementwith a metaloxide is carried out by directing the haloethane intoengagement with a metaloxide selected from the group includingCaO/CuO/TiO₂ and CUO/ZrO₂.
 17. The method according to claim 9 whereinthe step of directing the haloethane into engagement with a metaloxideis carried out by directing the haloethane into engagement with ametaloxide comprising CaO/CuO/TiO₂.
 18. The method according to claim 9wherein the mol ratios of the components of the metaloxide are 25% CaO,25% CuO, and 50% TiO₂.
 19. The method according to claim 9 wherein thestep of directing the haloethane into engagement with a metaloxide iscarried out by directing the haloethane into a metaloxide comprisingCuO/ZrO₂.
 20. The method according to claim 19 wherein the metaloxidecomprises a mol ratio of 50% CuO₂ and 50% Zr O₂.